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Welding Stresses in Rotor Shaft

A rotor shaft with a circumferential crack around the shaft was received for failure analysis

Procedure:

  • The rotor was visually inspected and photo documented.
  • The rotor was cut so that the fracture face could be visually inspected.

Conclusion:

The primary cause of failure was the residual stress state induced by terminating two welds in close proximity. This close placement of the termination points created a tensile stress in the shaft. Poor penetration of the welds was also exhibited, which acted as a stress riser.

rotor 1

rotor 2


Figures 1 and 2 – Visual inspection of the fracture face indicated that the fracture initiation site occurred between two weld termination points. Top View followed by Side View of weld zone.